Struct LateDataRetractionGenerator 

pub struct LateDataRetractionGenerator { /* private fields */ }

Generates retractions for late data corrections.

When late data arrives and updates an already-emitted window result, this generator produces:

1. A retraction (-1 weight) for the old result
2. An insert (+1 weight) for the new result

Example

use laminar_core::operator::changelog::LateDataRetractionGenerator;
use laminar_core::operator::window::WindowId;

let mut gen = LateDataRetractionGenerator::new(true);
let window_id = WindowId::new(0, 60000);

// First emission - no retraction needed
let result1 = gen.check_retraction(&window_id, b"count=5", 1000);
assert!(result1.is_none());

// Late data changes result - generates retraction
let result2 = gen.check_retraction(&window_id, b"count=7", 2000);
assert!(result2.is_some());
let (old, new) = result2.unwrap();
assert_eq!(old.as_slice(), b"count=5");
assert_eq!(new.as_slice(), b"count=7");

// Same result - no retraction
let result3 = gen.check_retraction(&window_id, b"count=7", 3000);
assert!(result3.is_none());

Implementations

impl LateDataRetractionGenerator

pub fn new(enabled: bool) -> Self

Creates a new generator.

pub fn disabled() -> Self

Creates a disabled generator (no-op).

pub fn is_enabled(&self) -> bool

Returns true if retraction generation is enabled.

pub fn set_enabled(&mut self, enabled: bool)

Enables or disables retraction generation.

pub fn check_retraction( &mut self, window_id: &WindowId, new_data: &[u8], timestamp: i64, ) -> Option<(Vec<u8>, Vec<u8>)>

Checks if we need to generate a retraction for this window.

Returns Some((old_data, new_data)) if the window was previously emitted with different data. Returns None if this is the first emission or the data hasn’t changed.

pub fn check_retraction_ref( &mut self, window_id: &WindowId, new_data: &[u8], timestamp: i64, ) -> Option<Vec<u8>>

Checks for retraction and returns borrowed slices (avoiding allocation when no retraction is needed).

Returns Some(old_data) if retraction is needed. The caller should then emit the retraction for old_data and insert for new_data.

pub fn cleanup_window(&mut self, window_id: &WindowId)

Cleans up state for closed windows.

Call this when a window is closed to prevent unbounded memory growth.

pub fn cleanup_before_watermark(&mut self, watermark: i64)

Cleans up state for windows that ended before the given watermark.

This should be called periodically to bound memory usage.

pub fn retractions_generated(&self) -> u64

Returns the number of retractions generated.

pub fn windows_tracked(&self) -> usize

Returns the number of windows currently being tracked.

pub fn reset_metrics(&mut self)

Resets all metrics.

pub fn clear(&mut self)

Clears all tracked state.

Trait Implementations

impl Default for LateDataRetractionGenerator

fn default() -> Self

Returns the “default value” for a type.